Techniques for enhancing vertebral bands in age estimation of California elasmobranchs

Description

Vertebrae from 1,152 elasmobranchs representing 22 species were collected between 1979 and 1981 to assess methods of enhancing incremental growth bands for age estimation. Thus far, we have tested methods previouslyreported in the literature, and have developed new procedures to enhance growth increments on 684 individuals of 14 species of elasmobranchs. Silver nitrate impregnation, X-radiograpby, and cedarwood oil clearing were the most successful techniques. Less effeetive were alizarin red staining, paraffin impregnation, alcohol immersiorn, and formic acid etching. Methods for preparing vertebrae and enhancing and counting growth increments are presented, and the problems associated with interpreting tile annual nature of such counts are discussed.

Iron, primary production and carbon-nitrogen flux studies during the JGOFS North Atlantic bloom experiment,

Description

Primary production was measured every other day towards the end (18-31 May) of the 1989 North Atlantic spring bloom. Rates varied with light and averaged 90.4 mmol C m -2 day -1 at the 47°N, 20°W station. Productivities measured south of Iceland (59°30′N, 20°45′W) were somewhat lower, averaging 83.6 mmol C m -2 day -1. Carbon and nitrogen fluxes were estimated using free-floating, VERTEX type particle trap arrays. To obtain mean rates representative of the North Atlantic spring bloom, flux data from three trap deployments were combined and fitted to normalized power functions:. mmol C m -2 day -1 = 14.35 (z/100) -0.946, mmol N m -2 day -1 = 2.34(z/100) -1.02, with depth z in meters. Regeneration rates were:. mmol C m -2 day -1 = 0.136(z/100) -1.946, mmol N m -2 day -1 = 0.0239(z/100) -2.02. The carbon export rate from the upper 35 m for the entire NABE study period (24 April to 1 June) was 39 mmol m -2 day -1. This value divided by the averaged productivity for the entire study (86 mmol N m -2 day -1) gave an F-ratio of 0.45. Concentrations of Cu, Fe, Ni, Pb and Zn were determined in water samples provided by JGOFS NABE scientists involved with primary productivity measurements. Although little contamination was observed for Cu, Ni and Pb, relatively large amounts of Zn (10 nmol kg -1) were found in some cases. In subsequent studies it was learned that this quantity of Zn can depress productivity rates by 25%. North Atlantic dissolved Fe concentrations were similar to those occurring in the Pacific (surface = 0.07; deep = 0.5-0.6 nmol kg -1). Although no evidence of Fe deficiency was found in enrichment experiments, the addition of nmol amounts of Fe did increase CO 2 uptake and POC formation by factors of 1.3-1.7. In this region, most of the phytoplankton's Fe requirement is probably met via the lateral transport of Fe from distant continental margins., Cited By (since 1996):170, CODEN: DSROE, ,

Although Fe is an element of great biological 1 and geochemical 2 importance, little is known about its distribution in the sea. The reasons for this are: (1) contamination is extremely difficult to avoid during sampling and laboratory procedures, not only because of man's wide use of this element, but also because it is fourth most abundant element in the Earth's crust (5.63%) 3; (2) the chemistry of Fe is very complex, and its form (or forms) in seawater is poorly known, hence whether one preconcentration technique will work for existing species is questionable. Iron also appears to be very insoluble 4 in oxygenated ocean water, and most (90%) 5 precipitates out in association with dissolved organics during estuarine mixing processes 5-8. Indeed, some argue that truly dissolved Fe does not exist in seawater and that the fraction found in filtrates is totally colloidal 9. We have been attempting oceanic dissolved Fe measurements for the past four years and report here three vertical Fe profiles (Fig. 1) that have the following features in common: Fe is severely depleted (0.15-0.30 nmol kg -1) in surface waters; Fe maxima (up to 2.6 nmol kg -1) occur in association with oxygen minima; and, Fe levels appear to vary little in mid-depth waters (0.5-1.0 nmol kg -1)., Cited By (since 1996):33, ,

The geographic distribution of mercury concentrations in the California mussel Mytilus californianus, collected from 1977-1978 at 43 sites along the western coastline of the continental United States is marked by consistently elevated levels at two locations. These two sites, which are relatively isolated from anthropogenic inputs and mercury-rich minerals, both contain large pinniped and marine bird populations. The relatively elevated mercury levels measured in the excrement of a pinniped from one of those locales indicate that the concentrated discharge of mercury-rich waste products from the marine ecosystem's top carnivores is contaminating lower trophic levels., Cited By (since 1996):1, Ecology, CODEN: MBIOA, ,

Enrichment experiments were performed in the Ross Sea to test the hypothesis that iron deficiency is responsible for the phytoplankton's failure to use up the luxuriant major nutrient supplies found in these and all other offshore Antarctic ocean waters. The results suggest that Fe deficiency is the primary reason that the present-day southern ocean biological pump is shut off. In contrast, iron was 50 times more abundant during the last glacial maximum; greater Fe availability may have stimulated the biological pump and contributed to the ice age drawdown of atmospheric CO 2. These results also imply that large-scale southern ocean Fe fertilization is feasible, at least in terms of the total amounts of Fe required; i.e., 100 000 to 500 000 tons yr -1., Cited By (since 1996):277, , , Downloaded from: http://onlinelibrary.wiley.com/doi/10.1029/GB004i001p00005/pdf (9 June 2014).

Leatherback turtles (Dermochelys coriacea) undergo substantial cyclical changes in body condition between foraging and nesting. Ultrasonography has been used to measure subcutaneous fat as an indicator of body condition in many species but has not been applied in sea turtles. To validate this technique in leatherback turtles, ultrasound images were obtained from 36 live-captured and dead-stranded immature and adult turtles from foraging and nesting areas in the Pacific and Atlantic oceans. Ultrasound measurements were compared with direct measurements from surgical biopsy or necropsy. Tissue architecture was confirmed histologically in a subset of turtles. The dorsal shoulder region provided the best site for differentiation of tissues. Maximum fat depth values with the front flipper in a neutral (45–90°) position demonstrated good correlation with direct measurements. Ultrasound-derived fat measurements may be used in the future for quantitative assessment of body condition as an index of health in this critically endangered species.

Excess major nutrients occur in offshore areas ranging from the tropical equatorial Pacific to the polar Antarctic. In spite of the great ecological differences in these environments, they share a common trait: iron deficiency. All of these areas are far from Fe-rich terrestrial sources and atmospheric dust loads in these regions are amongst the lowest in the world. Experiments were performed in three nutrient-rich areas: The Gulf of Alaska, the Ross Sea, and the equatorial Pacific. In general, populations without added Fe doubled at rates 11-40% of the expected maxima at various temperatures. The addition of nanomole quantities of Fe increased these doubling rates by factors of 2-3. In spite of the lack of Fe, tightly coupled phytoplankton/zooplankton communities seem to inhabit these major nutrient-rich areas. -from Authors, Cited By (since 1996):341, Oceanography, , , Downloaded from: aslo.org/lo/toc/vol_36/issue_8/1793.pdf (16 June 2014).

An interesting oceanographic problem concerns the excess major plant nutrients (PO 4, NO 3, SiO 3) occurring in offshore surface waters of the Antarctic 1-3 and north-east Pacific subarctic Oceans 4. In a previous study 5, we presented indirect evidence suggesting that inadequate Fe input was responsible for this limitation of growth; recently we had the opportunity to seek direct evidence for this hypothesis in the north-east Pacific subarctic. We report here that the addition of nmol amounts of dissolved iron resulted in the nearly complete utilization of excess NO 3, whereas in the controls-without added Fe-only 25% of the available NO 3 was used. We also observed that the amounts of chlorophyll in the phytoplankton increased in proportion to the Fe added. We conclude that Fe deficiency is limiting phytoplankton growth in these major-nutrient-rich waters., Cited By (since 1996):854, ,

Several explanations for the 200 to 280 ppm glacial/interglacial change in atmospheric CO2 concentrations deal with variations in southern ocean phytoplankton productivity and the related use or nonuse of major plant nutrients. An hypothesis is presented herein in which arguments are made that new productivity in today's southern ocean (7.4 × 1013 g yr-1) is limited by iron deficiency, and hence the phytoplankton are unable to take advantage of the excess surface nitrate/phosphate that, if used, could result in total southern ocean new production of 2.3 × 1015 g C yr-1. As a consequence of Fe-limited new productivity, Holocene interglacial CO2 levels (preindustrial) are as high as they were during the last interglacial (~ 280 ppm). -from Author, Cited By (since 1996):759, ,

This paper presents current information concerning the formation, make-up, distribution and transport of biogenic particles in the belief that this knowledge will provide greater understanding of the role of these particles in the cycling of trace elements., Oceanography, CODEN: NCSFD, ,

The California State Mussel Watch program is a long-term monitoring program conducted by the State Water Resources Control Board and the Department of Fish and Game. In a fifteen year time span, from 1977-1992, mussels were collected at 378 stations. From these stations, 47 were chosen to conduct statistical analysis based on the criteria that they had been sampled at least 6 times for total DDTs, total polychlorinated biphenyls (PCBs), and total chlordanes. Declines of total DDTs and chlordanes were noted at approximately half of the stations. Declines of total PCBs were noted at approximately one-quarter of the stations. Declines of PCBs but not DDTs in mussels near Los Angeles County's sewer discharge corresponded to declines of these contaminants in treated effluent., Cited By (since 1996):29, Invertebrates,
Ecology, CODEN: AECTC, ,

The measurement of primary production in the ocean is basic to biological oceanographic processes. Factors which control primary production are varied, but include micronutrients (i. e. , N and P) in sufficient supply, as well as many nanonutrients such as Cu, Mn and Zn. High levels of many of these trace constituents are toxic. Recent studies have shown that ambient concentrations of a number of nanonutrients in sea water are lower by an order of magnitude than previously believed., Cited By (since 1996):1, Oceanography, CODEN: NCSFD, ,

Mytilus californianus as a bioindicator of trace metal pollution: Variability and statistical considerations,

Description

Trace metal variability was evaluated in two populations of Mytilus californianus through the analysis of individual specimens. Samples were collected for two areas in the Southern California Bight and analysed for their Al, Cd, Cr, Cu, Fe, Ni, Pb and Zn content. Analysis of the data revealed that population variability was not the same between the two sites, indicating that variability may need to be evaluated for each population (site) studied. In general, the analysis of 10 to 30 individuals was necessary to yield maximum resolution in terms of trace metal concentrations between population means while maintaining cost effectiveness., Cited By (since 1996):29, CODEN: MPNBA, ,